The combination of multi-color HST imaging and extensive spectroscopy of massive galaxy clusters, from the inner core out to 2-3 viral radii, allow their dark matter and baryonic mass distribution to be derived independently using strong/weak-lensing techniques, galaxy dynamics and X-ray data. Specifically, the CLASH-VLT large programme has targeted 13 CLASH clusters (at z=0.2-0.6) spectroscopically identifying 500-1200 galaxy members per cluster, as well as many multiply lensed systems. Additional VLT/MUSE integral-field spectroscopy, in some cases, has provided a complete view of the central 300-400 kpc, velocity dispersions of cluster galaxies and secured an unprecedented large number of multiple images. With this combined data set, we show how to derive robust mass density profiles of the DM and baryonic components over three decades in radius and to investigate the innermost structure of these clusters. We compare these results with predictions of LCDM cosmological simulations. In addition, by exploiting lensing magnification on Hubble Frontier Field data and the unparalleled sensitivity of MUSE, we have unveiled a population of very faint, low-mass (10^6 Msun) Lyman-alpha sources at 3